Let's see your VE graph after tuning..
02-24-2005, 06:19 PM
#142
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Originally Posted by HumpinSS
Quick question how much % of error do NB's report or do we know
02-24-2005, 07:03 PM
#144
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Originally Posted by HumpinSS
I would argue they (NB) are no more accurate at 14.7 than a WB is throughout the curve. If this is true then who do we beleive and trust, the WB or the NB
02-27-2005, 05:08 PM
#148
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WOW! How did i miss this thread?
Here's some more fuel for the fire...
Tuning SD via WBO2 there are only a few golden rules:
1. Make absolutely sure your STFT's and LTFT's are off and report 0 at all times - if this is not the case you are wasting your time.
2. Ensure your WBO2 is up to correct operating temperature and is installed and calibrated correctly.
3. Ensure your injectors are calibrated correctly, remember you have 3 different ways to skin this cat and eliminating this one as "correct" is easy.
4. Ensure your timing is set to something reasonable (no point tuning fuel if you are hitting 5 deg timing)
5. set your commanded AFR to whatever you want it to be via openloop, PE, whatever tables. It really doesn't matter what you choose as the final result will be linear or very close to (ie. if your fuel is 5% rich when you are shooting for 12.8, then it will likely be the same 5% rich if you are shooting for 14.7). VERY IMPORTANT: if you do have large transitions between commanded AFR (eg. 14.7 to 12.5) you need to be aware of allowing for that transition in your tuning by holding a little longer after the transition has been made so that the averaging effect can ensure you plot enough points at the real load condition not the fuel transition.
6. mess with the VE until you get the commanded AFR within a few % of the measured AFR.
7. check your work by setting a different commanded AFR in the PE table and see how close the measured is. eg. set for 12.0 AFR you should see the WBO2 hit 12.0 as well. This is the beauty of having a correctly dialing in VE (airflow) component as you can now directly tweak your PE (or better still use the VCM Controls) to find out at what AFR (and spark) you make peak torque for each RPM. Note: remember there is a slight dependence of AFR on spark but nothing huge if you used reasonable timing values to begin with.
On the smoothness of VE tables...
The VE of an engine is determined by the acoustic propoerties of the inlet and exhaust manifolding and the dynamic flow properties of the valve etc. Generally the harmonic resonances are indeed "peaky" in ideal circumstances (very low loss, low order harmonic). However, in an LS1 intake/exhaust setup these resonances are way out at the top end of the RPM scale due to the short runner length. In fact most car makers go out of their way to avoid a peaky response. Also, with most traditional designs the loss of the system (due to high airflows thru small passages) really dampens everything to a large degree, also a reasonable sized plenum adds to that dampening effect. Putting all the resonances out of the normal operating ranges and also designing in things like smaller port areas to increase velocity and plenums to dampen harmonics and assist NVH - all lead to smoother VE curves.
However, as long as you are operating at steady state with a properly calibrated WBO2 (operating within its time response) the commanded AFR vs. measured AFR is the ultimate measure. Again, it is *very* unlikely you would see a relative difference between adjacent cells of more than a few %.
Larger camshafts with large overlap, you are mostly tuning around reversion effects and reversion related effects such as localised port heating. I haven't studied this reversion stuff in detail (since most newer engine designs have variable cam timing that eliminates all this and hence most experimentation has stopped and assumed "problem solved"), but the concepts looks at least a couple orders more complex to me (whenever i see chemical equations in physics problems i usually give up).
Hope that helps,
Chris...
Here's some more fuel for the fire...
Tuning SD via WBO2 there are only a few golden rules:
1. Make absolutely sure your STFT's and LTFT's are off and report 0 at all times - if this is not the case you are wasting your time.
2. Ensure your WBO2 is up to correct operating temperature and is installed and calibrated correctly.
3. Ensure your injectors are calibrated correctly, remember you have 3 different ways to skin this cat and eliminating this one as "correct" is easy.
4. Ensure your timing is set to something reasonable (no point tuning fuel if you are hitting 5 deg timing)
5. set your commanded AFR to whatever you want it to be via openloop, PE, whatever tables. It really doesn't matter what you choose as the final result will be linear or very close to (ie. if your fuel is 5% rich when you are shooting for 12.8, then it will likely be the same 5% rich if you are shooting for 14.7). VERY IMPORTANT: if you do have large transitions between commanded AFR (eg. 14.7 to 12.5) you need to be aware of allowing for that transition in your tuning by holding a little longer after the transition has been made so that the averaging effect can ensure you plot enough points at the real load condition not the fuel transition.
6. mess with the VE until you get the commanded AFR within a few % of the measured AFR.
7. check your work by setting a different commanded AFR in the PE table and see how close the measured is. eg. set for 12.0 AFR you should see the WBO2 hit 12.0 as well. This is the beauty of having a correctly dialing in VE (airflow) component as you can now directly tweak your PE (or better still use the VCM Controls) to find out at what AFR (and spark) you make peak torque for each RPM. Note: remember there is a slight dependence of AFR on spark but nothing huge if you used reasonable timing values to begin with.
On the smoothness of VE tables...
The VE of an engine is determined by the acoustic propoerties of the inlet and exhaust manifolding and the dynamic flow properties of the valve etc. Generally the harmonic resonances are indeed "peaky" in ideal circumstances (very low loss, low order harmonic). However, in an LS1 intake/exhaust setup these resonances are way out at the top end of the RPM scale due to the short runner length. In fact most car makers go out of their way to avoid a peaky response. Also, with most traditional designs the loss of the system (due to high airflows thru small passages) really dampens everything to a large degree, also a reasonable sized plenum adds to that dampening effect. Putting all the resonances out of the normal operating ranges and also designing in things like smaller port areas to increase velocity and plenums to dampen harmonics and assist NVH - all lead to smoother VE curves.
However, as long as you are operating at steady state with a properly calibrated WBO2 (operating within its time response) the commanded AFR vs. measured AFR is the ultimate measure. Again, it is *very* unlikely you would see a relative difference between adjacent cells of more than a few %.
Larger camshafts with large overlap, you are mostly tuning around reversion effects and reversion related effects such as localised port heating. I haven't studied this reversion stuff in detail (since most newer engine designs have variable cam timing that eliminates all this and hence most experimentation has stopped and assumed "problem solved"), but the concepts looks at least a couple orders more complex to me (whenever i see chemical equations in physics problems i usually give up).
Hope that helps,
Chris...
07-02-2005, 01:12 PM
#149
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Ive noticed some peoples ve tables reach a plateau at upper rpms and are completely flat there after, while other ve tables have a hump where the peak seems to be at max torque, then goes down into a plateau, like a ridge in the middle of the graph.
Anyone have any thoughts on this, which is better?
Anyone have any thoughts on this, which is better?
07-04-2005, 01:07 AM
#150
Whatever your car calls for is the best. There is no "be all end all" table to go by. I have tried numerous times to get my table baby back smooth and it is not needed. You can get it really close, but there will still be some ridges and peaks in it in places.
08-05-2005, 09:03 AM
#151
Originally Posted by Another_User
Professional tuners. I have never seen a professionally tuned VE table that was worth a crap. But I haven't seen any Aussie tunes...
Originally Posted by HumpinSS
..And after looking at a few professional tunes i am not convinced i want anyone comming near my car with a laptop besides myself
Originally Posted by AgentOrange
as stated before I wouldn't want anyone touching my stuff after reviewing some of these tunes. after seeing what Mr. Wright did for me three years ago I feel like some tuners are the biggest scammers in the industry.
Originally Posted by Black02SS
Thats right, if it can be done in an hour and 8 dyno runs without taking it on the road, it must be right. 
08-05-2005, 05:57 PM
#152
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Good thread. I spent the better part of the day reading the whole damn thing. 
The first pic is the best I could do using LTFT's. I got frustrated and parked the car until I aquired a WB02. All my fuel trims were negative, but the car really drove like ****.
The second pic is my VE table after a few passes in OLSD using my WB. The bird was driving MUCH better, but still not to my liking.
The third pic is where I'm at today. The more I log, the smoother my table gets. The bird is driving like a bat out of hell now.
The first pic is the best I could do using LTFT's. I got frustrated and parked the car until I aquired a WB02. All my fuel trims were negative, but the car really drove like ****.
The second pic is my VE table after a few passes in OLSD using my WB. The bird was driving MUCH better, but still not to my liking.
The third pic is where I'm at today. The more I log, the smoother my table gets. The bird is driving like a bat out of hell now.
